In:
Journal of Clinical Microbiology, American Society for Microbiology, Vol. 39, No. 9 ( 2001-09), p. 3092-3098
Abstract:
The COBAS AMPLICOR CT/NG test for Neisseria gonorrhoeae cross-reacts with certain strains of nonpathogenic Neisseria species. In some strains, the target sequence is identical to that of N. gonorrhoeae , whereas other strains have a small number of mismatches within the regions recognized by the primers or probe used in the COBAS AMPLICOR NG test. These cross-reactive strains are occasionally present in urogenital specimens, causing false-positive results in the COBAS AMPLICOR NG test. Analysis of the data generated in a large multicenter clinical trial showed that 2.9% of the specimens gave signals between A 660 s of 0.2 and 3.5 but that one-half of these equivocal specimens did not contain N. gonorrhoeae . Most of these equivocal specimens were correctly classified as true positive or true negative by retesting in duplicate and defining a PCR-positive result as two of three results with an A 660 of ≥2.0. If specimens had been classified as positive or negative based on a single test result using a cutoff of an A 660 of 0.2, specificity would have ranged from 96.2 to 98.9% depending on specimen type, sex, and presence of symptoms. By employing the equivocal zone-retesting algorithm, specificity increased to 98.6 to 99.9% with little effect (0.1 to 4.9% decrease) on sensitivity in most specimen types, enabling the test to achieve a positive predictive value of at least 90% in populations with a prevalence of 4% or higher. In lower-prevalence populations, the test could be used to screen for presumptive infections that would have to be confirmed by an independent test.
Type of Medium:
Online Resource
ISSN:
0095-1137
,
1098-660X
DOI:
10.1128/JCM.39.9.3092-3098.2001
Language:
English
Publisher:
American Society for Microbiology
Publication Date:
2001
detail.hit.zdb_id:
1498353-9
SSG:
12
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